Sow Pre-Farrowing Nesting Behaviour and Welfare

The nesting drive in pre-farrowing sows is one of the strongest motivational states observed in farmed animals. Denying sows the ability to build a nest before giving birth causes significant frustration and stress that affects both sow and piglet welfare outcomes.

Key Facts

Wild and feral sows spend 6 to 12 hours constructing a nest before farrowing, gathering grass, leaves, and twigs to create an insulated birth site
The nesting drive peaks 24 to 12 hours before farrowing and is driven by surging oxytocin and prolactin levels
Sows denied nesting material show vacuum nesting behaviour — stereotypic rooting movements on bare concrete — for hours before parturition
Provision of nesting material reduces pre-farrowing restlessness, shortens labour duration, and reduces piglet crushing rates in some studies
Loose-farrowing systems that allow sow movement combined with straw provision show lower stillbirth rates than crates with no nesting material

Welfare Considerations

Vacuum nesting in barren farrowing crates represents a severe motivational conflict that causes measurable physiological stress at one of the most demanding moments in the production cycle. Frustrated nesting motivation correlates with elevated cortisol, increased farrowing duration, and higher piglet mortality. The welfare case for providing nesting material — even in crated systems where straw or jute sacks can be provided — is strong. Transitioning to loose-farrowing systems removes the crate constraint entirely and allows expression of the full nesting and maternal behavioural sequence.

What You Can Do

Choose pork products from systems that commit to loose-farrowing or crated systems with verified nesting material provision
Ask retailers for evidence that their pork suppliers provide nesting material to sows before farrowing
Support campaigns for regulatory requirements mandating nesting material as a minimum standard in all farrowing systems
Donate to pig welfare charities working on the evidence base and policy advocacy for loose-farrowing adoption
Write to major food companies asking about their sow farrowing welfare commitments and transition timelines